This invention relates to a soot filter for cleaning the exhaust from an internal combustion engine, comprising sets of, for example three to five, filter tubes disposed in a circle axially parallel to one another, closed at one end and provided at the other end with a clean gas outlet opening, and composed of refractory ceramic yarn wound spool-wise to form hollow cylinders through which exhaust flows radially from the outside in, and a filter housing which has at least one inlet chamber at the closed ends of the filter tubes and at least one clean-gas manifold chamber at the other ends into which the clean gas outlet openings lead.
Such a soot filter is described in German Patent No. DE 30 07 642. No mention is made therein, however, of the possibility of cleaning such filters by burning off the soot collected in the filter core.
A variety of methods are known for burning off soot from the filter inserts of soot filters. These include the elimination of the soot by microwaves (German Patent No. DE 30 24 539), by providing an igniter and delivering fuel in which case the filter can be divided and cleaned alternately (German Published Application No. DE 37 25 587), by applying ignition adjuvants to the collected soot so as to reduce its flash point (German Patent No. DE 31 11 228), and by heating with electrical energy (German Published Application No. DE 37 12 333). The present invention relates to this last-mentioned type of cleaning filter tubes with electrical energy.